Various hybrid powertrain architectures are known for managing the input and output torques of various prime-movers in hybrid vehicles, most commonly internal combustion engines and electric machines. One such hybrid powertrain architecture comprises a two-mode, compound-split, electro-mechanical transmission which utilizes an input member for receiving power from a prime mover power source and an output member for delivering power from the transmission. First and second motor/generators are operatively connected to an energy storage device for interchanging electrical power between the storage device and the first and second motor/generators. A control unit is provided for regulating the electrical power interchange between the energy storage device and the first and second motor/generators. The control unit also regulates electrical power interchange between the first and second motor/generators.
Engineers implementing powertrain systems encounter driveline vibrations, which typically range from unnoticeable to objectionable to an operator. Driveline vibrations are customer dissatisfiers, and may reduce service life of one or more driveline components. Typically, engineers attempt to manage driveline vibrations by implementing systems which operate to cancel torque oscillations at one specific frequency, or over a range of frequencies, or a set of frequencies chosen based upon gear ratio at which the driveline is currently operating. Such torque cancellation systems typically pass driveline inputs through signal conditioning filters, which slow system responsiveness. Slow system response often leads to a bump or overshoot that occurs when there is an aggressive operator torque request, due to delays in transient responses required to develop filters. Such systems often use a single feedback variable, typically engine speed, and command a single control signal, typically engine torque. However, single feedback/single control vibration control systems do not provide adequate damping in a system having multiple devices operable to generate vibrations in a driveline.
A hybrid powertrain system is exemplary of a system having multiple devices operable to generate vibrations in a driveline, which therefore drives a need for an alternative method and apparatus to control driveline vibrations. Feedback from such a driveline system which has multiple, varying operating states can be accomplished with a plurality of sensing devices operable to monitor and determine parameters for the operating states. However, some operating states may be difficult to sense directly, due to a lack of ability to directly sense certain operating states, e.g. torque, and added cost and complexity required to implement such sensing systems.
Therefore, there is a need to for a method and apparatus to estimate parameters of operating states of a hybrid driveline system, especially for operation of a vehicle equipped with a hybrid driveline that incorporates manual transmission configurations such as direct connection between an engine, torque-generative electric motors, and transmission input shafts.